A 0.35-μm subthreshold CMOS ASIC for a Smart Contact Lens Eye-Tracker.

This paper describes a camera-less eye-tracker using an instrumented contact lens fitted with photodetectors and illuminated by eyewear. The gaze direction is computed on the lens using the photo-currents by means of a mixed signal 0.35$-\mu$m CMOS ASIC. NFC is used to power the ASIC and to transmit the gaze direction to the eyewear. Experimental measurements are performed using a prototype scleral contact lens mounted on a mock-up eye. The measurements show that an accuracy of 0.2$^{\mathrm{\circ}}$ is achievable, i.e. 2.5 times better than current mobile video-based eye-trackers, for a power consumption of 170 $\mu$W. Several tests were carried out on several ASICs, demonstrating system reliability despite process variations, operating time, and supply voltage variations.